Machine



Sept. 2Q, 1960 o. H. JOHNSON ET AL 2,953,057

MACHINE Filed Jan. 18, 1957 8 Sheets-Sheet 1 FlG l AGENT p 19% o. H. JOHNSON ETAL 2,953,057

MACHINE 8 Sheets-Sheet 3 Filed Jan. 18, 1957 INVENTORS EDGAR HERMAN SCHMIDT ORVILLE HOWARD JOHNSON BY 4, s 7,

44; AGENT S R O T m V m 8 Sheets-Sheet 5 EDGAR HERMAN SCHMIDT ORVILLE HOWARD JOHNSON AGENT w. A a

Filed Jan. 18, 1957 o. H. JOHNSON ETI'AL 2,953,057

MACHINE Filed Jan. 18, 1957 8 Sheets-Sheet 6 EDGAR HERMAN SCHMIDT ORVILLE HOWARD JOHNSON AGENT o. H. JOHNSON ETAL 2,953,057

MACHINE Filed Jan. 18, 1957 8 Sheets-Sheet 7 INVENTORS EDGAR HERNAN SCHMIDT ORVILLE HOWARD JOHNSON BY X946 AGENT o. H. JOHNSON ET AL 2,953,057

MACHINE Sept. 20, 1960 Filed Jan. 18, 1957 8 Sheets-Sheet 8 2,953,557 Patented Sept. 20, 1960 Fire MACHINE Orville Howard Johnson and Edgar Herman Schmidt,

Wilmington, DeL, assignors to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed Jan. 18, 1957, Ser. No. 634,858

11 Claims. (CI. 86-20) This invention relates to a loading mechanism and more particularly to a device for loading and tamping explosive compositions into shells.

Dynamite and similar explosive cartridges are generally prepared by loading empty tubular shells with an explosive compositon, which can be either granular or gelatin, by means of reciprocating tamp arms. The loading machines normally employ a plurality of tamp arms each of which simultaneously tamps explosive into an empty shell. The density of the loaded composition is normally regulated by controlling the frequency and impact of the tamping strokes.

Known loading machines have several disadvantages. First, the time required for each cycle of the tamp arms does not change as the shells are filled; therefore, it takes as long to pack a portion of the charge in the bottom of each shell as it does to pack the last portion of the charge in the nearly filled shell. Secondly, most machines, especially those in which the tamps are driven frictionally, make an extra stroke after each set of shells is filled to reset the tamp arms to pack the charge in the bottom of the next set of empty shells. Thirdly, in most known loading machines, the efficiency of the machines decreases with the length of the shells packed.

It is an object of this invention to provide a shell load ing machine which charges shells rapidly and efiiciently. Another object of this invention is to provide a loading machine in which the time for each stroke decreases as the shells are filled. Still another object of this machine is to provide a machine the efliciency of which is substantially independent of the size of the shells charged. A further object is to provide a machine which will pack all shells to substantially the same even density. A still further object is to provide a novel loading machine and to advance the art. These and other objects will become apparent in the course of the following specification.

These and other objects of this invention are accomplished by providing, in a shell loading machine, the combination which comprises a plurality of fluid-driven tamping means, an independently fluid driven crosshead positioned to meter the forward and rearward motion of the tamping means, and means to decrease the length of time of succeeding packing strokes of the tamping means as the shells are filled. More particularly, the loading machine of this invention comprises a frame, a plurality of pneumatically driven tamp arms, a hydraulically driven crosshead movably secured to the frame and positioned to meter the forward and rearward motion of the tamp arms, and means to decrease the length of time of each stroke of the tamp arms as the shells are filled.

The invention is described in detail hereinafter by reference to a preferred embodiment shown in the accompanying drawings wherein:

Figure 1 is a plan view of the machine.

Figure 2 is a side elevation of the machine.

Figure 3 is a cross-sectional view of the machine along line 33 in Figure 1.

Figure 4 is an enlarged plan view of the reciprocating crosshead.

Figures 5 and 6 are end-elevation and side-elevation views respectively of the crosshead stopping and reversing mechanism.

Figure 7 is an enlarged cross-sectional view of the tamp manifold and the upper portion of the tamp arms.

Figure 8 is a cross-sectional vertical elevation of the explosive feed mechanism.

Figure 9 is a cross-sectional view taken along line 2-2 of Figure 8.

Figures 10 and 11 are side elevation and end elevation views respectively of a device which causes the machine to make intermittent short strokes and packing strokes.

In Figures 1, 2 and 3, crosshead 1 is movably secured through rollers 2, 3 and 4 to frame 5 of the loading machine. Hydraulic cylinders 6 and 7 are fixed to frame 5. The rod ends of pistons S and 9, which operate within cylinders 6 and 7 are fixed to crosshead 1. Hydraulic pressure can be applied to either the head or rod ends of the cylinders to drive crosshead 1 forward or backward respectively along frame 5. This hydraulic pressure is applied to cylinders 6 and 7 by hydraulic pump 24 which is controlled by air signals sent to the pump by various valves on the loading machine as described hereinafter.

The particular means used to supply fluid to the hydraulic cylinders 6 and 7 forms no part of this invention. Standard variable displacement two-way hydraulic pumps, such as the Oil Gear pump manufactured by the Oil Gear Company, are preferred. The Oil Gear pump is controlled by air cylinders which are, in turn, controlled by the air signals from the loading machine. Other automatically controlled hydraulic pumps or combinations of hydraulic pumps can also be used. Electric and hydraulic signalling systems can be substituted for the air signals described in the disclosed embodiment; however, for packing high explosives the air signals are preferred.

In the particular embodiment shown in the drawings, the tamp assembly consists of tamp cylinders 10, tamp pistons 11, tamp tubes 12, and tamp tips 13. Tamp pistons 11, tamp tubes 12 and tamp tips 13 are coupled together to give a set of continuous tamp arms. Alternatively, unitary tamp arms can be used. Air is supplied through manifold 14 to the head end of tamp pistons 11 forcing the tamp arms consisting of tamp pistons 11, tamp tubes 12 and tamp tips 13 forward. Except when crosshead 1 is at the forward end of its stroke, tamp cams 15 fastened to the tamp arms at the head end of each tamp tube 12 abut against crosshead 1; thus, the crosshead 1 limits the forward motion of the tamp arms. Figure 7 shows an enlarged cross-section of the manifold 14, and the upper portion of the tamp arms. It also shows the abutment of earns 15 on the crosshead 1.

In Figures 1, 2 and 3, pneumatic cylinders 16 and 17 are secured to frame 5, and pistons 18 and 19, which operate within these cylinders, are fastened to crosshead 1. The total working area on the rod side of pistons 18 and 19 is equal to the total working area on the head side of the tamp pistons 11. These two areas are connected to the same closed air circuit through manifold 14 so that as the crosshead 1 moves forward and air is forced out of the rod end of cylinders 16 and 17, air is forced into head end of the tamp cylinders 10. Air in this closed circuit is maintained at an elevated pressure by a control valve connected to the air supply. Pistons 18 and 19 in pneumatic cylinders 16 and 17 thus balance the force exerted on crosshead 1 by cams 15 and permit hydraulic pistons 8 and 9 to work against a load throughout the entire cycle of the machine.

When large diameter shells are loaded, alternate tamp arms are held back by bar 20; thus the total working area on the heads of the operating tamp pistons 11 is reduced. For packing these large shells, thepneumatic cylinders 16 and 17 are disconnected from the closed air circuit by valve 21 and allowed to run free. The force on the crosshead 1 of the tamp earns 15 of the operating tamp arms is balanced by a third pneumatic cylinder 22 which is fastened to crosshead 1. Piston 23, fastened to frame 5, has a hollow piston rod which, when large diameter shells are filled, is connected in the closed air circuit supplying tamp cylinders 10. When the crosshead 1 moves forward carrying cylinder 22 forward, air is forced out of cylinder 22 through piston 23 and manifold 14 into the tamp cylinders 10. The working area on piston 23 is equal to the working area on the alternate tamp pistons 11; therefore, piston 23 in cylinder 22 acts to balance the load on the crosshead 1 in a manner similar to pistons 18 and 19 in pneumatic cylinders 16 and 17.

Rocker beam 30 is rotatably mounted on rod 31 fixed to crosshead 1. The rear edge of this beam carries a set of rollers 32 (see Figure 3), each of which rides on one of the earns 15. Arm 33 attached to rocker beam 30 actuates the stopping and reversing mechanism (see Figures and 6).

Figure 4 is an enlarged plan view of the crosshead 1. Air valve 40 fixed to frame 5 is actuated by cam 41 secured to crosshead 1. As the crosshead 1 approaches the rear end of its stroke, cam 41 engages valve 40 which reverses hydraulic pump 24 that feeds hydraulic cylinders 6 and 7. This decelerates and stops crosshead 1, and accelerates it on the forward stroke.

Cam 42 adjustably mounted on crosshead 1 engages air valve 43. fixed to frame 5 on the forward stroke of the crosshead 1. The position of cam 42 determines the maximum forward stroke of the crosshead 1 and tamp tips 13 when the machine first begins to load empty shells. In addition, by reversing the crosshead 1, it prevents the tamp tips 13 from striking the bottom of the empty shells. After a small amount of powder has been packed in shells 65, air valve 44, which is connected in parallel with air valve 43, begins to reverse crosshead 1. At this point cam 42 no longer moves far enough forward to contact valve 43 and the crosshead 1 controlled by valve 44 reverses progressively earlier in each cycle.

As shown in Figures 5 and 6, when the crosshead 1 and the tamp arms move forward at the beginning of each stroke of the machine, rollers 32 on rocker beam 30 (see also Figures 1, 2 and 3) ride on tamp cams 15'. When the forward motion of the tamps is stopped by the packed charge in shells 65, crosshead 1 continues forward and rollers 32 ride off of cams 15, thus actuating rocker beam 30, raising arm 33 and allowing valve 44, which is also attached to crosshead 1, to extend. When valve 44 extends, it reverses pump 24 and starts crosshead 1 backward. As crosshead 1 picks up the tamp arms again on the backward stroke rollers 32 again ride up on cams 15 and valve 44 is ready for the next forward stroke.

Arm 33 also depresses valve 47 which is attached to crosshead 1. When valve 47 extends, signals are set up so that valve 40 shifts pump 24 into neutral at the end of the next rearward stroke of crosshead 1, thereby stopping the flow of fluid to hydraulic cylinders 6 and 7 and stopping crosshead 1. Clip 48 is rotatably secured to crosshead. 1 through pin 49. Cam follower 50 which rides on cam '51 fixed to frame 5, holds the top of clip 48away from valve 47 until crosshead 1 allows tamp tips 13 to enter the part of the shells 65 that is to be packed (see Figure 9). When the tamp tips 13 enter this region, cam follower 50' rides off of cam 51 and spring 52 forces the top of clip 48 over valve 47. In this manner, as long as at least one of the shells 65 is not filled, arm 33 holds valve 47 down until crosshead 1 moves forward to allow tamp tips 13' to enter the one or 'more unfilled shells. When the tamp tips 13 enter the shells 65, clip 48 holds valve 47 depressed. After thetamp tips 13' have been stopped by the packed charge, arm 33 rises and releases valve 44 causing crosshead 1 to make another stroke. If all of the shells 65 are filled, when tamp tips 13 contact the packed charge, rollers 32 move off cams 15 allowing arm 33 to rise and valve 44 to extend, but, since crosshead 1 is not far enough forward, cam 51 still keeps the' upper portion of clip 48 away from valve 47. Since neither arm 33 nor clip 48 hold valve 47: down, valve 47 extends and shifts pump 24 to neutral and, indirectly, stops crosshead 1v at the end of its next rearward stroke. After valve 47 extends, crosshead 1 continues forward and is reversed on its last stroke by valve 44. Since valve 47 is already extended, the upper portion of clip 48 merely rests against the side of the cap on valve 47" when crosshead 1 is in its forward-most position and does not depress valve 47.

The explosive feed mechanism shown in Figures 8 and9 is described in more detail in copendingapplication Serial No. 534,498, filed by Edgar H. Schmidt on Sept. 15, 1955, now abandoned. This assembly, which is positioned at the forward end of the loading machine (see Figures 1 and 2), comprises essentially a stirrer 60 which rotates within hopper 61 to feed explosive 62 into the boreholes 63 of nipple plate 64. Shells 65 held by a V groove shuttle 66 or other suitable means are slipped over replaceable nipples 67. Tamp tips 13 pick up the explosive falling through channels 68 into boreholes 63 and carry it into shells 65. Stirrer 60 can be operated either continuously or intermittently. However, it is preferable to stop the stirrer 60 while the tamp tips 13 are inside theshells 65. This intermittent operation can be controlled by valve 69 (see Figure 2) which is actuated by a cam oncrosshead 1.

Throughout the charging cycle, tamp tips 13 remain within the boreholes 63. Relief slots 70 are cut in nipple plate 64 to help prevent explosive from Wedging the tamp tipe 13 in the boreholes 63.

Various ancillary features have been added to the loading machine to ensure safe operation and to facilitate operation under special conditions. Valves 71 and 72 (see Figs 1 and 2), contact and stop crosshead 1 on the forward and rearward strokes respectively if,

it is not reversed by the normal reversing mechanism. A manually operated air valve (not shown) is connected in parallel with valve 47 so that the machine operator can stop the machine at any time. An air control can be added to cause crosshead 1 to dwell between the end of the rearward stroke and the start of the forward stroke. With certain types of explosives, this is advantageous since it allows more time for the stirrer 60 to force explosive into the boreholes 63. A barricade 73 can also be placed behind the feeding and packing area to shield this area from the rest of the machine.

Tamp tips '13 are coupled to tamp tubes 12 with Dardelet threads so that if one of the tamp tips 13 sticks and all the force of crosshead 1 is exerted on that tam-p tip on the rearward stroke, the Dardelet coupling will pull apart, usually with a force of about 500 pounds. This coupling prevents the crosshead 1 from stalling or breaking some element of the machine if one of the tamp ti'ps13 sticks. Dardelet threads are a modified form of buttress screw threads in which the driving face of the threads is made perpendicular to the axis of the screw, as in a square thread, while the back face of the threads makes an angle with the axis as in a V- thread. Threaded couplings provided with such Dardelet threads are particularly adapted to withstand heavy thrust on the perpendicular driving face during packing strokes, yet will pull apart when the coupling is subjected to tension.

Another feature which can be added to the machine of this invention is a device for causing the machine to make intermittent packing strokes and short strokes. When the crosshead 1 is operated at high speeds, such d as for example, 180 feet per minute, it is often difiicult to pack a low-density or soft charge in the shells 65. This problem is solved by providing one or more short strokes of the tamp arms between each packing stroke. During each short stroke, tamp tips 13 move forward just far enough to push a plug of powder out of nipples 67, then during the next packing stroke the tamp tips 13 pack the accumulated charge into shells 65 as previously described.

The device for controlling the aforementioned intermittent packing stroke and short stroke operation is shown in Figures 4, 10 and 11. Air valve 80 fixed to frame is connected in parallel with reversing valves 43 and 44. Like valves 43 and 44, valve 80 can reverse hydraulic pump 24, hence crosshead 1, on the forward stroke, Air valve 80 isactuated by qam 81 on crosshead 1. Air valve tit) is energized (i.e., is connected in parallel with valves 43 and 44), by valve 82. When valve 82 is depressed, valve 80 is deenergized, thus crosshead 1 is reversed on its forward stroke either by valve 43 or valve 44, and the machine makes a packing stroke as previously described. When valve 82 is extended, valve 80 is energized and, since during the forward stroke valve 81) is actuated before either valves 43 or 44, it reverses crosshead 1 as soon as the tamp tips 13 approach the end of nipples 67.

As shown in Figures and 11, valve 82 is actuated by rotating cam 33, which is fastened to axle 84. Ratchet cam 85 is connected to the other end of axle 84. Roller 86 is mounted at the end of piston 87 which operates within pneumatic cylinder 88. Air is supplied alternately to the head and rod ends of piston 37. Each time piston 87 moves forward, roller 86 forces ratchet cam 85 ahead one station. Frictional clutch 89 applies enough load to axle 84 so that roller 86 rides back to the next preceding ratchet when air is supplied to the rod end of piston 87. Although air is preferred, some fluid other than air, such as water or oil, can be used to drive piston 87.

The supply of air to the head and rod ends of piston 87 is controlled by the same signals which reverse crosshead 1. Valve 41) causes air to flow into the head end of cylinder 88 when crosshead 1 completes its rearward stroke thereby indexing ratchet cam 85 one station. Valve 43, 44 or 80 cause air to flow to the rod end of cylinder 88 when crosshead 1 has completed its forward stroke. If air cylinders are used to shift the hydraulic pump 24 which supplies fluid to hydraulic cylinders 6 and 7, the air to drive piston 87 can be tapped from the air cylinders which shift pump 24.

By increasing or decreasing the angular spacing between projections 90 on rotating cam 83, the number of short strokes per long or packing stroke can be increased or decreased.

Briefly, the operating procedure for the loading machine just described consists of first positioning shells 65 over nipples 67 on nipple plate 64 and supplying air under pressure to the closed air circuit including tamp cylinders 10, manifold 14- and pneumatic cylinders 16 and 17. Next, stirrer 6d and pump 24 are started. Pump 24 forces fluid, preferably oil, into the head end of hydraulic cylinders 6 and 7 moving crosshead 1 forward. At the same time, the air pressure against tamp pistons 11 pushes the tamp arms forward and keeps tamp cams abutted against crosshead 1. As tamp tips 13 proceed through boreholes 63, they pick up explosive 62 and pack it into the bottom of shells 65.

When tamp tips 13 have almost reached the bottom of the shells 65, cam 42 on crosshead 1 contacts valve 43 and reverses pump 24 so that pressure is applied to the rod ends of cylinders 6 and 7. This stops and reverses the motion of crosshead 1. As crosshead 1 starts on its rearward stroke, it carries the tamp arms backward with it withdrawing tamp tips 13 from shells 65. When the crosshead 1 nears the rear end of the machine, cam

6 41 actuates valve 40 and starts the crosshead 1 on the next forward stroke.

Tamp tips 13 carry explosive forward into shells 65 until the packed charge stops the forward motion of the tamp arms; therefore, the end of the tamp tips 13 stop closer to the mouth of the shells 65 on each successive stroke of the machine.

When the tamp arms are stopped by the charge in the .shells 65, the crosshead 1 continues forward until it is reversed by valve 43. Simultaneously, rollers 32 on rocker beam 30 begin to roll off tamp earns 15 on the tamp arms. After the machine has completed two or three cycles, rollers 32 ride completely off tamp cams 15 and, from then until all the shells are filled, valve 44 actuated by arm 33 on rocker beam 30 reverses the crosshead 1. As the shells 65 fill and the tamp arms stop at a point closer to the rear of the machine on each stroke, cross-head 1 reverses earlier in each stroke. Consequently, since the rate of flow of fluid to the rod and head ends of hydraulic cylinders 6 and 7 remains constant during the whole loading operation, the time of each cycle of the crosshead 1 and tamp arms decreases as the shells 65 are filled. Typically, for shells 1 /2 inches in diameter and 30 inches long, the cycle time decreases from 2.6 seconds for the first cycle to 1 second for the last cycle.

If one of the shells does not fill as rapidly as the others, the crosshead does not. reverse until the tamp .tip 13 feeding that particular shell is stopped. The reason for this is that all the rollers 32 must ride off all the tamp cams 15 before arm 33 will allow valve 44 to extend and reverse the crosshead 1.

Since each of the tamp arms is individually pressured and is not fastened to crosshead 1, the pressure on the explosive in each shell 65 is the same whether or not the shells 65 fill at the same rate. When all the shells 65 are full, valve 47 extends on the forward stroke and the crosshead 1 stops on the next rearward stroke. The filled shells are then removed from the nipples 67 and crimped.

When dilferent sizes of shells are to be charged, nipple plate 64, nipples 67, and tamp tips 13 are merely changed to fit the diameter of the shells. Tamp tips 13 fill essentially the entire cross-section of the boreholes 63. When large diameter shells are packed, all the shells 65, boreholes 63 and tamp tips 13 cannot be aligned in front of the plurality of closely spaced tamp arms; therefore, alternate tamp tips 13 are removed and the unused tamp arms are held back by projections on bar 20.

All parts which move or contact moving parts near the explosive are constructed or protected with wood, nonferrous metals and alloys, moldable polymers and synthetic resins or other suitable non-sparking materials. Tamp tips of heavy wood are preferred. The ines which feed fluid to hydraulic cylinders 6 and 7 and air to manifold 14 and pneumatic cylinders 16, 17 and 22 can be constructed of standard steel pipe. Rubber, plastic or other flexible tubing can be used for the lines which feed air signals from the various control valves on the machine to the variable displacement 2-way hydraulic pump 24.

The loading machine of this invention charges a wide variety of sizes of shells rapidly and eificiently. Because the length and time of each stroke decreases as the shells are filled, the machine can often charge shells up to 2 /2 times as fast as other known machines. Since the tamp arms are driven independently of the crosshead and since the crosshead reverses shortly after the tamp arms pack the explosive, the machine of this invention is much more efficient than loading machines which drive tamp arms by frictional contact with a crosshead which has a stroke of fixed length. In addition, because all of the tamp arms are driven independently from a common closed air circuit, all shells are packed with the same even pressure.

The particular embodiment just described in detail is particularly suitable for packing shells ranging from A3 of an inch to 3 inches in diameter and from 6 to 30 inches in length. The density of the packed explosive can be regulated easily by varying the crosshead speed and the air pressure in the closed air circuit feeding the tamp cylinders; typical tamp pressures range from 10 to 50 p.s.i.g.

We claim:

1. A shell loading machine comprising a frame, a plurality of pneumatically driven tamp arms, a hydraulically driven crosshead movably secured to said frame and positionedto meter the forward and rearward motion of said tamp arms, and means, responsive, to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells comprising a control means for reversing the hydraulic force on said crosshead at a fixed point in its rearward stroke and a control means for reversing the hydraulic force on said crosshead during its forward stroke, said control means for reversing the hydraulic force on said crosshead during its forward stroke being fixed to said crosshead and actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms.

2. A shell loading machine comprising a frame, a plurality of pneumatically driven tamp arms, a hydraulically driven crosshead movably secured to said frame and positioned to meter the forward and rearward motion of said tamp arms, and means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells which comprises a control means for reversing the hydraulic force on said crosshead at a fixed point in its rearward stroke and a control means for reversing the hydraulic force on said crosshead during its forward stroke, said control means for reversing the hydraulic force on said crosshead during its forward stroke being fixed to said crosshead and actuated by an arm fastened to a rocker beam rotatably mounted on said crosshead, said rocker beam having attached thereto a plurality of rollers each of which rides on a cam fixed to one of said tamp arms.

3. A shell loading machine comprising a frame, a hydraulically driven crosshead movably secured to said frame, a plurality of pneumatically driven tamp arms each of which carries a cam positioned to abut against said crosshead during its forward and rearward motion, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms, and means attached to said crosshead and positioned to exert a pneumatic force on said crosshead to balance the force on said crosshead of said cams fixed to said tamp arms.

4. A shell loading machine comprising a frame, a hydraulically driven crosshead movably secured to said frame, a plurality of pneumatically driven tamp arms each of which carries a cam positioned to abut against said crosshead during its forward and rearward motion, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms, and means positioned to exert a pneumatic force on said crosshead to balance the force on said crosshead of said cams fixed to said tamp arms comprising a pneumatic cylinder attached to each side of said frame and a piston operating within each of said cylinders and attached to said crosshead.

5. A shell loading machine comprising a frame, a hydraulically driven crosshead movably secured to said frame, a plurality of pneumatically driven tamp arms each of which carries a cam positioned to abut against said crosshead during its forward and rearward motion, means, responsivevto relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms, and means positioned to exert a pneumatic force on said crosshead to balance the force on said crosshead of said cams fixed to said tamp arms comprising a pneumatic cylinder fixed to said crosshead and a piston operating within said cylinder and fixed to said frame.

6. A shell loading machine comprising a frame, a hydraulically driven crosshead movably secured to said frame, a plurality of pneumatically driven tamp arms, each of which carries a cam positioned to abut against said crosshead during its forward and rearward motion, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms, means attached to said crosshead and positioned to exert a pneumatic force on said crosshead to balance the force on said crosshead of said cams fixed to said tamp arms and means to stop said shell loading machine when said shells are substantially filled actuated by means rotatably secured to said crosshead coacting with means fixed to said frame.

7. A shell loading machine comprising a frame, a hydraulically driven crosshead movably secured to said frame, a plurality of pneumatically driven tamp arms each of which carries a cam positioned to abut against said crosshead during its forward and rearward motion, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms, means attached to said crosshead and positioned to exert a pneumatic force on said crosshead to balance the force on said crosshead of said cams fixed to said tamp arms and means to stop said shell loading machine when said shells are substantially filled comprising a valve, fixed to said crosshead, which, when extended, stops the hydraulic driving force on said crosshead, means to hold said valve depressed until said tamp arms are stopped by the packed charge in said shells, a clip rotatably mounted on said crosshead and positioned to hold said valve depressed while the forward ends of said tamp arms are within said shells and a cam fixed to said frame and positioned to force said clip away from said valve when said ends of said tamp arms are not Within said shells.

8. A shell loading machine comprising a frame, a hydraulically driven crosshead movably secured to said frame, a plurality of pneumatically driven tamp arms each of which carries a cam positioned to abut against said crosshead during its forward and rearward motion, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms, means attached to said crosshead and positioned to exert a pneumaiic force on said crosshead to balance the force on said crosshead of said cams fixed to said tamp arms, means to stop said shell loading machine when said shells are substantially filled actuated by means rotatably secured to said crosshead coacting with means fixed to said frame, means to prevent said tamp arms from striking the bottom of substantially empty shells actuated by means fixed to said crosshead coacting with means fixed to said frame and a feeding means adapted to feed charge in front of said tamp arms before said tamp arms enter said shells.

9. A shell loading machine comprising a frame, a hydraulically driven crosshead movably secured to said frame, a plurality of pneumatically driven tamp arms each of which carries a cam positioned to abut against said crosshead during its forward and rearward motion, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells actuated by means rotatably mounted on said crosshead and in movable contact with said tamp arms, means attached to said crosshead and positioned to exert a pneumatic force on said crosshead to balance the force on said crosshead of said cams fixed to said tamp arms, means to stop said shell loading machine when said shells are substantially filled actuated by means rotatably secured to said crosshead coacting with means fixed to said frame, means to prevent said tamp arms from striking the bottom of substantially empty shell comprising a control means fixed to said frame for reversing the hydraulic force on said crosshead during its forward stroke actuated by a cam adjustably mounted on said crosshead and a feeding means adapted to feed charge in front of said tamp arms before said tamp arms enter said shells.

10. A shell loading machine comprising a frame, a plurality of pneumatically driven tamp arms, a hydraulically driven crosshead movably secured to said frame and positioned to meter the forward and rearward motion of said tamp arms, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells and a feeding means adapted to feed charge in front of said tamp arms before said tamp arms enter said shells in combination with a means fixed to said frame for reversing said shell loading machine actuated by said crosshead during its forward stroke at least once between each of said cycles during which said tamp arms pack shells as soon as said tamp arms have pushed said charge from said feeding means thereby causing said shell loading machine to make at least one short stroke between each packing stroke.

11. A shell loading machine comprising a frame, a plurality of pneumatically driven tamp arms, a hydraulically driven crosshead movably secured to said frame and positioned to meter the forward and rearward motion of said tamp arms, means, responsive to relative movement between said crosshead and said tamp arms during the forward motion thereof, to decrease the time of succeeding cycles of said crosshead and said tamp arms during which said tamp arms pack shells and a feeding means adapted to feed charge in front of said tamp arms before said tamp arms enter said shells in combination with a means Which causes said shell loading machine to make at least one short stroke between each packing stroke comprising a reversing control means fixed to said frame and actuated by said crosshead of said shell loading machine on its forward stroke, a valve which energizes said reversing control means, a rotating cam positioned to actuate said energizing valve and secured to an axle, a ratchet cam secured to said axle, and a pneumatically driven piston positioned to turn said ratchet cam a fixed amount corresponding to each stroke of said crosshead of said shell loading machine.

References Cited in the file of this patent UNITED STATES PATENTS 2,404,434 Clark et al. July 23, 1946 2,515,323 Stuart July 18, 1950 2,775,987 Bohlman et al. Jan. 1, 1957 FOREIGN PATENTS 383,710 Italy Oct, 23, 1940 

